Sintering Mechanism of Self-fluxed Sinter with Basicity of About 1.2

Abstract

Process of mineral formation of sinter with a basicity of about 1.2 was studied by specimens obtained from the sintering-interruption experiment, re-treatment (re-heating) of commercially produced sinter and various test-pan sinter test. Phase of sinter, which was fired well, consisted of magnetite and silicate glass. Peterogeneity and deficiency of firing were reflected in the distribution of the calcium ferrites. The mechanism of sintering was elucidated theoretically by using phase diagrams. Formation of liquid at relatively lower temperature depended on a oxygen potential (Fe⁺⁺/Fe⁺⁺⁺ ratio) of the condensed system; in the case of higher oxygen potential, liquid of calcium ferrite (β) was formed and in the case of lower potential, liquid of silicate (γ) was formed. At initial stage of the sintering process (in the case of basicity about 1.2) more amount of liquid of calcium ferrte (β) was formed than that of liquid of silicate (γ), but at the latter stage, liquid of silicate (γ) increased by transition of Fe⁺⁺⁺ to Fe+⁺. higher temperature these two kinds of liquid reacted each other and interacted and liquid of calcium ferrite (β) tended to decrease. The proper phase of well-fired sinter consisted of magnetite and silicate, which resulted in well assimilation of these liquids.